Hormones- Class 7 Flashcards
What are hormones?
Secretions that may produce a response at a near/remote site. Their actions are selective and effective at very minute quantities.
What are 3 types of endocrine hormones?
-Proteins
-Steroid
-Aromatic Amine hormones
What is the source of polypeptide hormones?
Hypothalamus and pituitary glands
Oxytocin
ADH
GnRH
TSH
FSH
LH
hCG
How do polypeptide hormones get into cells?
Membrane bound receptors.
Do polypeptide hormones use transport proteins?
No.
What is special about LH, FSH, TSH (structurally)?
Dimers
- alpha subunits that are identical
-B chains differ to gives specificity
What characteristic is exploited to test for different polypeptide hormones like LH, FSH, and TSH?
Their different beta chains
What are steroids made from?
Cholesterol
What are the steroids that bud from cholesterol?
-Testosterone
-Progesterone
-Estradiol
-Androstenediol
Do steroids use transport proteins?
Yes- sex hormone binding globulin SHBG
What kind of receptors do steroids use?
Intracellular specific receptors
- Cytoplasmic receptors
-Nuclear receptors
What are the types of receptors for steroids? 4
Androgen
Estrogen
Progesterone
Corticosteroid
How does mifepristone work?
It is an abortion pill that chemically structured to mimic progesterone.
What are examples of aromatic amines?
Epi and norepi
What are the three levels of control?
1= Target organs
2= Pituitary
3= Hypothalamus
What hormones are secreted from hypothalamus?
CRH
TRH
GHRH
GHIH
PRF
PIH
GnRH
What hormones are associated with the anterior lobe of the pituitary gland?
ACTH
TSH
GH
PRL
FSH
LH
What hormones are associated with the posterior pituitary gland?
ADH
Oxytocin
Explain the GH path
GHRH released from hypothalamus, anterior pituitary secretes GH, the liver breaks down glycogen and adipocytes break down triglycerides, and IGF stimulates amino acid uptake by target cells, promoting protein synthesis
Increas GH causes what pathologies?
Acromegaly
Gigantism
Decreased GH causes what pathology?
Dwarfism
What is acromegaly?
Rare chronic endocrine disorder resulting from hyper-secretion of GH
Cause is normally pituitary adenoma leading to abnormal musculoskeletal growth, most often noted in the face/extremities
GH can also be abused by?
Athletes and rich people
When is oxytocin secreted?
In response to suckling
What does oxytocin do in a female’s body?
Induces labor, controls postpartum uterine bleeding
What are medications that are synthetic forms of oxytocin?
Pitocin and Syntocinon
Both to induce labor
If osmolality increased by 1-2% what happens to ADH?
ADH increases 4 x
If osmolality decreased by 1-2% what happens to ADH?
ADH turns completely off
What are causes of hypofunction of the anterior pituitary gland?
Hypothalamic lesion
Pituitary adenoma like simmonds syndrom or sheehans
Postpartum hemmorrhage- hypovolemia
Genetic defect
If all labs for TSH, LH, FSH, (anterior pituitary lobe hormones) are low- what do you expect?
Panyhypopituitarism
How many layers does the adrenal gland have?
3
Zona glomerulosa
Zona fasciculata
Zona reticularis
What are major pathologies of the adrenal gland?
Cushings
Addisons
What is secreted from the adrenal medulla?q
Aromatic amines
EPI
NOREPI
What is synthesized in the zona fasiculata and how is it stimulated?
Cortisol and it is stimulated by ACTH
ACTH production is _. Cortisol peaks at _ AM
diurnal, 8:00
What is the composition of cortisol in plasma?
90% bound to CBG corticosteroid binding globulin, 10% is free (biologically active)
What is cortisol’s 1/2 life?
90 minutes
Where is CBG synthesized?
Liver and is dependent on estrogen
What is the pathway to making cortisol?
Cholesterol -> Pregnenolone -> progesteron -> 12-Hydroxyprogesterone -> 21-HYDROXYLASE ENZYME -> cortisol
What would happen during pregnancy if CBG is dependent on estrogen?
If estrogen increases so does CBG
How is cortisol measured?
Serum at 8:00 AM and rechecked at 4:00 PM
OR
Free cortisol can be checked by 24 hr urine specimen
What would the lab values for Addison’s disease look like?
Low cortisol, high ACTH
What are the symptoms of Addisons disease?
Weakness
weight loss
pigmentation of skin + mucus membranes*
Hypotension
Anorexia, naseau, vomiting
Salt Craving
Is addisons a primary secondary or tertiary endocrine defect?
Primary
What is the ACTH stimulation test
Tests Addisons Disease
Give ACTH
Test @ 30 min
Test again @ 60 min
If the cortisol level stays the same= primary Adrenal insufficiency (Addison’s disease)
What is the metyraprone test?
Metyrapone inhibits the 11 beta hydroxylase enzyme that is needed to make Cortisol.
Normally, the decrease in cortisol should stimulate the pituitary secretion of ACTH by the negative feedback mechanism
(Shouldn’t be used in pt’s with addisons)
What are three ways Cushing’s syndrome can be caused?
Hyperplasia of the adrenal gland,
Pituitary tumor,
Ectopic tumor causing adrenal gland to create more cortisol
What are symptoms of Cushing’s syndrome?
Obesity
Hypertension
Glucosuria
Polyuria
Menstrual/sexual dysfunction
Striae
Bruising
Psychiatric disturbances
Osteoporosis
Edema
What is the dexamethasone suppression test?
DEX is a synthetic cortisol.
You take 1 mg at 11:00 PM, cortisol is measured at 8:00 AM.
Normally, the high night cortisol should have turned off ACTH and lowered cortisol
Pts with Cushing’s will have no cortisol suppression. Problem: primary overproduction
